1. Field of the Invention
This invention relates to a dental X-ray irradiation indicating device which is used for dental or intra-oral X-ray photographing.
2. Description of the Prior Art
When an X-ray photograph of a tooth is to be taken, a dental or intra-oral X-ray film package (hereinafter referred to only as film package) is positioned inside of the tooth (on the side adjacent the tongue) for an object of photographing, and an X-ray is irradiated upon the tooth from the outside. In such X-ray photographing, it is necessary to hold a film package at the specific position during photographing. A conventional supporting device for holding a film package in position is described below with reference to FIG. 1 which is a sectional view of an oral cavity in which the supporting device is used.
Referring to FIG. 1, reference symbol 1a and 1b denote each a tooth, 1a.sub.1 and 1b.sub.1 denote each an occlusal surface, 2 denote gums, 3 a tongue, and 4 a cheek. Reference numeral 5 denotes a supporting device adapted to be bitten between the teeth 1a and 1b, and the supporting device 5 is made of a comparatively soft or flexible substance and has a shape of a parallelepiped having a rectangular cross section. Reference numeral 6 denotes a film package adhered to an end face of the supporting device 5, and 7 an X-ray film enclosed in the film package 6.
The supporting device 5 and the film package 6 are initially prepared independently of each other. In preparation for X-ray photographing, the supporting device 5 is adhered to a predetermined location of the film package 6, and then the film package 6 is inserted into the oral cavity and positioned at such a position as to allow an X-ray photograph of the tooth 1a to be taken. Then, the supporting device 5 is bitten between the teeth 1a and 1b so as to hold the film package 6 at the position. An X-ray is subsequently irradiated from the outside of the cheek 4 toward the tooth 1a as indicated by an arrow mark X. Consequently, an X-ray image (latent image) of the tooth 1a is produced on the X-ray film 7. The film package 6 is then taken out of the oral cavity, and the envelope or cover of the film package 6 is torn away to take out the X-ray film 7. The X-ray film 7 is then developed and fixed to produce a visible X-ray image of the tooth 1a on the X-ray film 7.
In such X-ray photographing as described above, however, it is not possible to accurately discriminate, from outside, the position of the X-ray film 7 and hence the position of the tooth 1a for an object of photographing, and it is quite impossible to discriminate the slope with which the X-ray film 7 is inclined by the gums contacting therewith. Accordingly, in conventional X-ray photographing, a photographer takes aim roughly at the position of the X-ray film 7 or the tooth 1a and directs an X-ray to the location. An X-ray image of the tooth 1a can be obtained even by such rough means because the X-ray diffuses to some degree. It is very troublesome, however, to take aim at the position of the X-ray film 7 or a tooth for an object of photographing from outside each time a photograph is to be taken. Besides, when the X-ray is stopped down in order to obtain a clearer X-ray image, mere taking aim may not permit accurate irradiation of the X-ray, and actually it is difficult to obtain a clear X-ray image. Further, normally the X-ray film 7 is inclined with respect to a vertical line interconnecting the upper and lower teeth 1a and 1b due to presence of the gums 2 as described above. In this instance, it is almost impossible to produce an image of the tooth 1a with the exact size on the X-ray film 7. There is the possibility, therefore, that the diagnosis and/or treatment depending upon the X-ray image may lack in accuracy.